 |
|
|
Nuclear Medicine Research
Deep Septic Thrombophlebitis:
An Unrecognized Cause of Relapsing Bacteremia in Patients With Cancer
Bacteremia is a serious complication in neutropenic cancer patients. While most cases are eradicated with a 2-week course of antibiotics, some recur, leading to significant morbidity and even death. The source of these relapsing infections remains unknown in more than a third of affected patients. Central venous catheter (CVC)-related deep venous thrombosis (DVT) is common in cancer patients, but is frequently unrecognized. Infection of the thrombus during a primary episode of bacteremia may result in the development of deep septic thrombophlebitis (STP), a severe infection that requires longer duration (4 weeks) of therapy to prevent complications. STP has not been recognized as a source of relapsing bacteremia in cancer patients. We have recently shown that fluorine-18 fluorodeoxyglucose positron emission tomography (FDG-PET) is a highly specific test for the diagnosis of septic thrombophlebitis. In this report, we demonstrate that STP in patients with cancer may represent a clinically silent focus of persistent infection following an episode of primary bacteremia, and that this infection can reactivate with a relapse of bacteremia following chemotherapy-induced bacteremia. Between April 2002 and May 2003, four patients with multiple myeloma developed STP in of the superior vena cava (SVC) and right subclavian vein (SCV). The diagnosis of STP was made in the presence of (1) high-grade bacteremia (persistently positive cultures for 3 days despite appropriate intravenous antibiotics); (2) DVT as diagnosed by duplex scan (DS) in areas amenable to DS evaluation; (3) abnormal FDG-PET uptake in a central vein (site of current or removed CVC); and (4) no other source of primary infection at another site, including endocarditis. Relapse of bacteremia was defined as recurrence of bacteremia with the same organism (same species and susceptibility), after 2 weeks of appropriate antibiotic therapy resulting in complete clinical response. All patients had an episode of primary bacteremia that responded to 2 weeks of appropriate antibiotics (and CVC removal in three patients). Before the initiation of additional chemotherapy, none of these patients had evidence of infection. FDG-PET scans obtained in two patients for myeloma staging revealed abnormal uptake within SVC and right SCV. Since both patients were a symptomatic, no antibiotics were given. Relapse of bacteremia was documented in all four patients during chemotherapy-induced neutropenia, and was complicated by septic embolization to lungs in one patient. The diagnosis of STP led to significant therapeutic changes for all four patients, including removal of the newly placed CVC (three patients) and longer (4 to 6 weeks) antibiotic course (four patients). All patients recovered without relapse of their infection and were able to resume therapy for their underlying disease. The DS was negative in all four patients, but a computed tomography scan of the chest in one patient revealed SVC narrowing and stricture indicative of DVT. This is the first report to suggest that clinically silent STP can represent a focus of serious infection in patients with cancer and that this focus can reactivate and cause a relapse of bacteremia following chemotherapy-induced neutropenia. Reactivation may develop in otherwise asymptomatic patients whose first bacteremic episode was apparently cured with appropriate antibiotics and CVC removal. The significant rate of relapsing bacteremia in cancer patients and the documentation of four cases in our patients throughout a short period, suggest that clinically silent STP may be responsible for a significant proportion of relapsing bacteremias. That DS was negative in our patients should not be surprising since DVT involved the SVC in three patients, an area not readily amenable to evaluation by DS. Our findings imply that the diagnosis of STP should be considered in cancer patients who experience a relapse of bacteremia. In the absence of a documented source of recurrence, such patients should undergo evaluation by DS and FDG-PET. In addition, the presence of abnormal FDG-PET uptake in a central vein in a patient with prior bacteremia should raise the index of suspicion for STP, even when symptoms of infection are not present.
[view pdf* of article]
Return to Nuclear Medicine Introduction
|
||||||||||||||||||||||||||||||||||||||||||
